Machine for welding tubular objects



,May 10, 1932- c. G. L. sJLANDER 1,857,338

MACHINE FOR WELDING lTUBULAR OBJECTS Filed May 22, 1929 6 Sheets-Sheet 1 j m 41f ff g; f W

May 10, 1932. c. G. l.. sJLANDER 158.57338 MACHINE FOR WELDING TUBULAR OBJECTS v y Filed May 22, 1929. 6 Sheets-Sheet 2 May l0, 1932. c. G. L. SJLANDER MACHINE EOE WELDING TUBULAR OBJECTS 6 Sheets-Sheet 3 Zven/Zvaf" Filed May 22, 1929 C22/Z ZI. [j'la ifdef- May 10, 1932. c'. G. L. SJLANDER 1,857,338

MACHINE FOR WELDING TUBULAR OBJECTS Filed May 22, 1929 6 Sheets-sheet 4 May 10, .1932. c. Gf L. SJLANDER i 1,357,338

` MACHINE FOR WELDING TUBULAR OBJECTS Filed May 22, 1929 e sheets-sheet 5 May 10, 1 932.-

c. 3. 1 SJLANDER 1,857,338

MACHINE FOR WELDING TUBULAR OBJECTS 6 Sheets-Sheet 6 Filed May 22, 1929 Patented May 10, 1932 lUNITED s'mrss CARL GUSTAE LEONARD SJLNDER, @F DBLSBOBG, SWEDEN' MACHINE FOR WELDmG TUBULE @BEECTS Application led Hay 22, 1929, Serial No. 365,088, and in @wetten May 23 1923.

1 lo ing the cost and the work with their maintenance to a minimum.

This is reachedsubstantially by giving the inner electrode about the smallest diameter which its mechanical durability permits.

Thus the contact area between the electrodes and the work becomes smaller, and consequently the resistance and the heat become greater at a smaller expenditure of energy. At the same time a smaller pressure can be 2 0 usedl between the work and the electrodes,

which in its turnhasan advantageous influence especiallyv upon the durability of the outerselectrodes.

The inner electrode gains in strength and 2 5 durability: (1) by being made of a solid copper-bar, (2) by being given'a slow motion to-and-ro in axial direction. during rolling against the inside ofthe tubular work, (3) by such proportioning thatthe electrode after `a large number of revolutions, comes back to the same position which itrhad at a previous time, (4) by making Yrovision whereby the part of the electrode-'t t comes into contact i A with the work ismnedcinstead of cylindrical. Due to theseatcr provisions, the electrode after 4l'aavingieen used a certain time may be put in its original state by cutting off a plece of the conical part.

The invention is` illustrated in the accompanying drawings, which show an embodiment of the weldingmachine, which as usual is provided with a parted outer electrode which may be opened and closed. i

-Fig. 1 is a vertical section through a. `,weld- 4 55- ing;r aggregate.

Fig. 2 is a section on line II-II of Fig. 1. Fig. 3 is a section on line III- III of Fig. 1. Fig. 4 is a section on line IV--IV of Fig. 1. Fig. 5 is-a ,section on line V-V of Fig. 1. 59 Fig. 6 is a front view of the machine with two welding aggregates, showing a radiator mounted in the machine, and the .outer electrode closed in the one aggregate and open in the other. Figs. 7, 8 are end views of the left weld" 55 aggregate with closed and open outer electrode, respectively.

Figs. 9, 10 and 11 are connecting diagrams for the weld transformer.

The machine contains two identical weld oo aggregates in order that the two necks of one section may 'n welded one immediately after the other without displacing the radiator. These aggregates may be connected to a common or to dierent transformers.

On account of the wear of the electrodes it is impracticable to keep the electrode groups identically equal, therefore it is important that the welding be not done at the same time in the two aggregates.

The two halves 1 and 2 of the outer electrode, Figs. 1, 6 and 7, are by means of clamps 41, of the weld transformer.

The inner electrode 11, Figs. 1, 3, 4, 5 and 6, which is cylindrical, is journalled with a. certain inclination in a part 12, Figs. 1, 3, 4 and 5, which by means of a. ring 13, Fig. 1,

.consisting of thin sheets of metal, is movably and electrically connected with the part 14, Figs. 1,'4 and 5. The part 14 is rotatably journalled in the frame part 15, Figs. 1. 4, 5 and 6. The part 15 is by means of the bar 16, Figs. 1, 6 and 7 electrically connected with` the end 18, Figs. 1 and 6, of the secondary` winding 48 of the4 transformer. The parts 7 and 15 are insulated from each other by .insulation 19, Fig. 1, insulation tubes a and insulation plates b on the bolts c with which the two parts are connected. The part 14 has at its one end a worm wheel 20, Fig. 1, which is driven by the worm 22 mounted on the shaft 21, Fig. 1. A sleeve, Figs. 1 and 3, which embodies a toothed wheel 2 4, is fixed on the inner electrode 11, Fig. 1, 100

i means of a conical fixing sleeve 23 and a nut 28. Said toothed wheel 24 engages a stationary internally toothed ring 25, ligs. 1 and 3. On the sleeve of the toothed wheel 24 aroll 26 is rotatably journalled, Fig. I, which engages a cam groove 27 of a toothed ring 2 9 which is rotatably journalled in a stationary part 30, Fig. 1. The ring 29 is connected with the worm 22, Fig. 1, by means of a, toothed wheel 31, its shaft c and the worm wheel 32, and said ring 29 is therefore driven by said worm 22..

The part 33 of the inner electrode 11 which l comes into contact with the neck n, Figs.

1, 6 and 7, is conical, and the conicity and the inclination of the elect-rode in the part 12, Fig. 1, are suchthat the generatrix of the cone which .is in contact with the neck is almost parallel with the axis of the part 14 and thus at right angles to the central planesof the radiator sections, which planes are transverse to the connection channels k. There exist, of course, small variations in the relative ositions of the electrode end 33 and the ra iator necks on account of wear and differences in the thickness of metal,

-' but they are so small that they have no in- 'luence upon the quality of the weld.

The slides 5 and 6, Figs. 1 and 6, can by means of bars 35 and 36, Figs.-6 and 7, be moved up and down thus closing and opening each outer-electrode. The bars 35 and 36 receive their motion from cam discs 41 and 42 on the shaft 43 byl means -of levers 44, 45, 46, Figs. 6, 7 and 8. The cam disc shaft 43 is by means of suitable gearing (not shown) connected with the shaft 21, Figs. 1,

Y means of a clutch-coupling.

6, 7 and8.

The inner electrode 11 is pressed against the work by springs 37, Fig. 5, with the aid of hoops 38 and 39 and a pin `40, Figs-1 and 5, which pin rests against the part 12. The

latter has llimited play within the part 14, Figs. 1, 4 and 5," so that it may scillate a. little vertically by deflection in the laminated sheet metal ring 13.

If two radiatorsetions 34 are to be welded together, the outer' electrode is'irst closed about the section necks n, the one of ,which has been pushed into the other. Then the primar)J7 circuit 47 of thel transformer is ,closed, and immediately' aft-er that the worm 22 is started, for instance by being in a known way connected-to the shaft 21, Fig. 1, by Then the part 14 has made one turn',-the coupling between the shaft 21 and the worm screw 22 is discon- 'nected, after which the outer electrode opens and remains in the opened position.v lVhile the part 14 rotates, the centre of the conical part 33 of the inner electrode 11 describes a circle about the centre of the section necks n. while said conical part- 33 rolls against the inside ofthe inner neck 11.

ready said/this planetary movement has been As has been alknown before. By choosin the number of the teeth in the toothed w eel 24 and the part 25 so that they stand to each other about as the diameter of the inner electrode to the inner diameter of the Work, the rotation of the inner electrode relative to the work, takes place almost as a true rollingmotion, but

the friction between the inner electrode and the work becomes, of course, considerably smaller than with a rolling motion 4caused only by friction. Onaccount of this the part 29 should rotate with a speed a little de! viating from'the Arotation speed of the part 14, i. e.' a little slower or a ,little faster. The part 29 obtains, as has been mentioned above, its motion from the worm 22. 'v

By the axial movement of the inner electrode the forming of grooves in the working surface of the electrode is avoided. The inner electrode is, however. gradually worn off. This wear having proceeded as far as can be :practically allowed, a piece of the conical part of the inner electrode is cut otf, and the electrode is movedl forward' a distance corresponding to the length ofthe cut-oil' piece, after the nut 28 has been loosened. The electrode is then fixed in its new position by tighteningthe nut 28.'

By making the inner electrode flong, the abovefmentioned cuttingfo and moving-forward may be repeated many times, and the same electrode may thus be useda long time. Thepossibility of utilizing the inner electrodeto the utmost in the simple way mentioned is due to giving the electrode a conical working surface. and journalling it obliqu'ely in the part 12. By the oblique journalling one gains also the advantage,l that the inner electrode clears that part of the radiator s ection neck, which faces the machine.` Y

A further feat-ure which contributes tomaking the inner electrode durable is so choosing the numbers of the teeth of the toothed wheel 24 and the ring 25 that they do not contain a factor common to both. Thus it takes longer before the same point of the inner electrode comes back to any one point. at which it'previouslycontacted with the work. If the rin;I 25 has 50 teeth and the toothed Awheel 24, for instance, 29 teeth. and the ratio A wear of the inner electrode becomes insignifine 'y of the teeth in the parts 25 and 29, on the contrary, been 50 and 30, 30 turns only would have been necessary. At a rat-io of gearing of 10: 9 or l0 1l between the parts lt and 29 the inner electrode makes a whole double stroke axially while the part 14 makes l0 turn. lt the same ratio of gearing were -tor instance 100: 99 or 100:111, 100 turns of the part 14 would be necessary in order that the electrode 10 should accomplish said double stroke. 3 rl'his ratio of'gearing is not critical, but experiments,`that have been made, have shown the ratio l: 9 to be a suitable ratio. lt should y be noticed, that the' electrode should go X neither too slow nor too fast. lt it goes veryr Slow, grooves are formed in the electrode, an

the purpose of the axial movement is defeat- `edr If it, on the contrary, goes too fast, the friction between the electrode and the work becomes so great that grooves are formed in the electrode-in consequence thereof, and the quality of the weld is hazarded on 'account of stresses in the work.

ln order that the machine shall be as easily managed as possible it is preferably proy vided with two identical welding aggregates, both substantially identical with the ene described above. however, shall take place with the greatest possible reliability and safety, it should not be done in the two aggregates at the same time, but in one immediately after the other so that the machine need not' be started more than once for each radiator section lto be welded to a previous section..

The machinefis preferably arranged'so that the outer electrode .of the second aggregate closes immediately after the outer electrode of the first aggregate begins to open. When 40 the Welding of one section has been carried n out, the outer electrodes in the two aggregates remain in the open position, so that the radiator may be removed and reinserted, to-

` gether with a new section. 45 As the weld heat arises on account of the resistance of the iron, and as-theresistance grows at increasing temperature, it has appeared, that if the same tension of the weld current is used at the start as well as at the continued welding of a section, the .welding at the very start becomes not as good as during the continuedwelding, because the temperature at the. start is not high enough. This depends partly on the fact, that the iron at the time for the start has lower temperature and consequently lower resistance, and vpartly on the fact, that the Contact surfaces between the electrodes and the workinglpiece at the start are not of the same form as after the start.

These factors co-operate to that point, that the weld heat becomes insufficient at the start, if the tension is not higher than that which is necessary for the continued welding. ln 'i order that the welding shall be of a reliable In order that vthe welding,

quality, the tension of the weld current is increased at the ystart as much as is necessary i'Eor a safe start welding, and is lowered to the tensiongwhich is suitableL for the continued welding iediately after the start.

Figs. 9, l0 and ll diagrammatically show means suitable for efect-ing the momentary alteration of the tension. i

'llliere are several contacts 1 7 in connection with the primary winding 47 Y of the transformer in order to make disconnection of a larger er smaller number of turns pos sible for the regulation of the secondary or weld tension. Vhen welding, the secondary winding 48 is connected tothe work over the v electrodes t9. Two machine-driven contact devices 50 and 5l, 54, 55 are arranged in the primary circuit. The' objectof the contact device 50 is to close the circuit at the start of the welding and to open itat the end of the welding. llt is regulated by a slowly rotating cam disc 52, which during one revolutien closes and opens the contact device 50 twice, once for each weld aggregate. Fig. 9 shows the position before the start. The con# tact part 5l, induenced by the spring 56 and regulated by a second slowly rotating cam disc 53, is then in contact withI the contact part 54, which at 5 is connected. to the winding #i7 in order to obtain a. little-higher secondary tension than the normal one."

it the start the position is the one shown in Fig. l0. 1 Shortly after that the contact part 5l on account of the influence of the spring 56 strikes against the contact part 55, which at another point, or instance at 3, is connected to the winding 47, and normal secondary tensioni, which is suitable orthe continued welding, is obtained. This position is shown in ltig. 11. 'lhe `construction of the cam discs 52, 53 show n in the draw`- ving presumes that they rotate synchronously. The described details may, of course, be constructed in many other ways and the machine may be used for welding together articles other than radiator necks.

ll claim:

l. ln an electrical welding machine for cirumerentally welding tubular objects, an electrode of less diameter than the internal diameter of the objects to be Welded and adapted for reception within the latter, and means for imparting a reciprocating axial movement to said electrode and for simultaneously` imparting a planetary movement thereto relative to the axis of the tubular objects.

2. lin an electrical welding machine for joining tubular objects, a rolling inner electrode, means for/rolling said electrode, means means embodying said electrode', and means los izo

along the inside of the Work; said inner electrode being journaled in an oblique position' with respect to the center line of the tubular work, the part of said'inner electrode Which is adapted tokcontact with the Work having a conical form in order to effectively engage the Work.

.4. In a Welding machine for tubular bodies, a'rotary driven member, an electrode extending through said member, and means ernbodying a pack of resilient sheet metal disks for establishing a driving connection between said member `and said electrode.

5. Ina weldin machine for tubular bodies, an inner rotatabll electrode, arotatable member carrying said electrode, means for driving said rotatable carryinor member, and additional means for rotatlng' said electrode lvgvith respect to said rotatable carrying memer. v

6. In a Welding machine for tubular bodies, a. rotatable and slidable inner electrode, a rotatable member carrying said electrode, means for driving said rotatable carrying member, means for rotating said electrode with respect to said carrying member, a roll mounted on said electrode, and a relatively stationary cvaln trackr engaging said roll to impart a longitudinal to and fro' movement to said electrode.

7. A structure as speciied in claim 6; said cam track being of annular form and being rotatably mounted, and means for rotating said cam track at a speed different from the speed of said carrying member.

8. In a Weldin g machine for tubular bodies, a rotatable sleeve and means for driving the saine, a Heating electrode-carrying mem'ber within said sleeve, a yieldable` driving connection between-said carrying member and said sleeve, `and a spring-contracted yoke surrounding said sleeve, said yoke having a portion passing through said sleeve and abutting said carrying member to laterally urge the latter for the purpose of holding the electrode against the Work.

9.' In avvvelding machine, a pair of'outer electrodes mounted for sliding toward and :from each other, links extending from and connected with said electrodes, rock shafts `ammesse co-acting ,with said shoes for actuatin said cranks, shafts and links to control sai electrodes. j

10. In a Welding machine for tubular objects, a rotatable carrying member, an inner electrode having a conical work-engaging en d, and means mounting said electrode on adjustment of the latter through said roll.-

In witness whereof I have hereunto signed my name.

CARL GUSTAF LEONARD SJLANDER.

having cranks to which said links are con= nected, said rock shafts having additional cranks provided with shoes, and rotary cams 

